Abstract
Purpose: To investigate the actinomycetes from an extreme environment for their inhibitory potential against methicillin-resistant Staphylococcus aureus (MRSA), and the metabolic fingerprinting of the active strains.Methods: A total of 80 actinomycetes strains were recovered from Cholistan desert, Pakistan. The isolated strains were identified by morphological, biochemical and physiological characterization and by 16S rRNA gene sequencing. The antimicrobial activity of the selected actinomycetes strains against MRSA was determined by agar well and disc diffusion assays. All the strains were screened against MRSA for the identification of potent antimicrobial producers. Further, validation of MRSA, strains was carried out using a portion of mec-A gene (533bp) of five strains including A1, A6, A7, A8 and A9, amplified and sequenced.Results: The desert actinomycetes strains exhibited promising antimicrobial activity against MRSA with zone of inhibition of up to 25 mm recorded in agar diffusion and disc diffusion assays. The MRSA strains also showed maximum genetic similarity with methicillin-resistant Staphylococcus aureus in GenBank. Most of the actinobacterial strains exhibited 99 % genetic similarity with the genus Streptomyces, including strains AFD6, AFD12, AFD23, AFD25, and AFD26 while isolate AFD18 has 100 % similarity with a Pseudonocardia, named Saccharothrix xinjiangensis.Conclusion: The results reveal that actinomycetes from the desert ecosystem studied are significant producers of useful antimicrobial agents, and should be explored further for novel drug candidates against MRSA.Keywords: Anti-MRSA potential, Actinomycetes, Extreme environments, Metabolic fingerprinting, 16S rRNA gene sequencing, Mec-A gene characterization
Highlights
The multidrug resistant (MDR) pathogens are increasing significantly and have proved as a global economic and healthcare crisis
The data from Pakistan suggested that 4 - 51 % of healthcare-associated S. aureus cases were reportedly caused by methicillin-resistant Staphylococcus aureus (MRSA)
The present study aims at the exploration of a unique and harsh ecosystem of desert in Pakistan, for the isolation and screening of actinomycetes for antimicrobial compounds against MRSA
Summary
The multidrug resistant (MDR) pathogens are increasing significantly and have proved as a global economic and healthcare crisis. For 16S rRNA gene sequencing, genomic DNA of selected desert actinomycete strains was isolated from mycelia, by using tissue genomic DNA kit (FavorPrepTM, Cat# FATGK001-1). The crude extracts of desert actinomycetes obtained by solvent extraction were spotted on TLC plates (TLC Silica gel 60 F254, Merck, Germany), which were developed with 5 % CH2Cl2/MeOH solvent system. For each of the sample, TLC plate was cut into two halves, one was used as a reference and sprayed with staining reagent (anisaldehyde/H2SO4) and the other half was placed inverted on the LB agar seeded with MRSA strain. This plate was incubated for 24 h at 37°C. The zone of inhibition was measured after incubation and the active components were compared with the reference plate, marked and were scanned [13]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
